Brake drum



W. H. FARR BRAKE DRUM Oct. 27, 1936.

Filed June 3, 1952 2 Sheets-Sheet 1 INVENTOR Wrremfivrw; BY

ATTORNEY W. H. FARR BRAKE DRUM Filed June 3, 1932 2 Sheets-Sheet 2 INVENTOR n l lllll r're'm 521m", av z i J 45 ATTORNEY result of this phenomenon.

Patented Oct. 27, 1936 1mm DRUM .Warren H. Farr, Detroit, Mich., assignor to Budd Wheel Company, Philadelphia, la., a corporation of Pennsylvania Application June 3, 1932, Serial No..615,1'l5

6 Claims. (Cl. 301-'-6) The invention relates to vehicle wheels and brakes, and particularly to methods of cooling and strengthening brake drums.

With modern road speeds becoming higher and necessitating braking of vehicles from high speeds, several difliculties have been encountered, particularly in adequately cooling brakedrums. The higher peripheral speeds of the brake drums,

wearing. against the brake linings, and the heat developed by high speed stops, cause the brake drums to become distorted and unequally expanded. Ineiiicient braking is the most usual Eiforts have been particularly directed to the adequate cooling of brake drums in order that the heat generated in drums may be dissipated. My efforts have been primarily directed to improvements in brake drum design in an eifort to correct the conditions which have existed and thereby make brakes more emcient in use.

The chief object of my invention is the provision of cooling means whereby the brake drum will tend to keep its normal shape throughout all ranges of temperature. An incidental object is the improvement in the manufacture of such drums. A still further object is the strengthening and improved design of brake drums.

Broadly, the objects of my invention have ure 1.,

Fig. 3 is a cross sectional view taken on line 3-3 of Figure 1. i

Fig. 4 is a partial elevational view of a modified form of my invention.

Fig. b is a detailed cross sectional view showing a vehicle wheel embodying my invention, the section being taken on line 55 of Figure 4.

Refening to the drawings by reference numerals and particularly to Figures 1 to 3, brake drum I is comprised of a cast metal braking ring II and a pressed metal mounting plate l2. In the preferred form of my invention, mounting plate I! is provided with an axially extending peripheral flange l3 which is imbedded in braking ring ll, adjacent an axial edge thereof.

Mounting plate I! is additionally provided with a radially extending portion i l having holes l5, through which the brake drum, as a whole, is

, mounted on the usual wheel hub, not shown.

According to my invention I provide a series of radially extending ribs IS on the exterior surface of braking ring II, which ribs extend angularly across the braking ring, in a spiral formation. These ribs are preferably of decreasing height toward the open end of braking ring II, for a purpose later to be explained.

The brake drum described above is preferably fabricated .by casting the braking ring II in a permanent mold by the centrifugal casting process. The flange l3 of. mounting plate i2 is inserted in the mold before the casting step, and the molten metal flows about this flange, bonding therewith, and affording an extremely-simple yet secure joinder between the two members. In cases where annular ribs are provided on the an exterior of braking ring ii the permanent mold process cannot be used satisfactorily because it is difficult to remove the finished ring axially "from the mold. By providing spiral ribs I6, ex-

tending transversely of the braking ring II, I am able to use the permanent mold process. The ribs form, in eflfect, threads on the braking ring,- and, as a consequence, the braking ring may be removed from the mold by rotating it relative thereto, virtually unscrewing it from the mold. so This provision is materially aided by the fact that the ribs are of decreasing height toward the open end of the ring, or, in other words, toward the inside of themold. It has been found in practice that it is merely necessary to lightly tap the casting to loosen it from the mold, and then unscrew it outwardly. The advantages of the permanent mold process are well known, and by my inventiomthe ribbed brake drum may be made by such a process.

The spiral ribs on braking ring ll tend to force air currents axially across the braking surface, thus conveying heat away from the brake drum. It will be seen that the ribs will be inclined toward the outside of the vehicle wheel in the proper relation in order to draw in cool air as the vehicle moves forwardly. Further, the spiral arrangement of ribs l6 provides additional rib surfaces for radiation. This factor is very important in connection with the cooling of the drum and the maintenance thereof in a truly cylindrical contour. thus increasing the effectiveness of the drum. In addition to the above advantages, ribs l6 strengthen the drum ring II in much the same way as do the webs of a channel member.

In the modification shown in Figures 4 and 5, hub I1 is provided with a radially extending flange l8 having an annular series of axially extending studs I9. Wheel body 20, preferably in the form of a disc, is provided with a radially extending portion 2| adapted to be secured to the front face of flange l8 and securing studs l9 by a series of cap nuts 22. The usual wheel rim 23 and retaining rings 24 and 25 are shown. An annular series of equally spaced holes 26 are provided in the body portion of the wheel 20.

At the rear face of hub flange I 8, brake drum 2! is mounted through a radially extending por tion 28 thereof, by means of jam nuts 29, which also secure the usual oil slinger 30. Drum 21, preferably of the cast type, is provided with an axially extending braking portion 3|, and a conical interconnection portion 32. A braking portion 3| terminates at the open end of the drum in a radially extending marginal flange 33 through which apertures 34 are provided.

Ribs 35, like ribs IS in the other figures, are provided on the exterior surface of the braking portion 3| and the interconnecting portion 32 of drum 21. -These ribs are preferably continuous, and as heretofore described are decreasing in height toward the open end of the drum. It will be seen that as the wheel rotates during forward movement of the vehicle the ribs 35 draw air through holes 26 in the wheel body forcing these cooling currents laterally across the exterior surface of braking portion 3|, and finally through apertures 34 in marginal flange 33 and thence outwardly past rim 23. As heretofore mentioned, the cooling effect provided by these ribs is not only characterized by the air currents which are induced thereby,'but also by the increased amount of radiation surface afforded.

It has been found that brake drums constructed in accordance with those shown in the various figures of the drawings have materially increased the efficiency and service life of vehicle brakes. A hitherto unknown degree of strength has been attained with a minimum of weight, primarily by virtue of the spiral ribs incorporated in the various figures. The drums have been found to maintain their true cylindrical form under the most severe braking conditions.

It will be seen that the objects of my invention have been attained in full. Cooling, radiation, and strength have been afforded by the provision of the spiral ribs on the braking portions of the various drums, and themanufacture of the drums has been simplified thereby. The decreasing height of the ribs toward the free edge of the drum not only facilitates the spiral draw of the casting from the mold by immediately releasing the edges of the ribs from the mold, but also prevents undue pocketing of the air at the free edge of the drum between the ribs, decreases the resistance to air circulation, and improves the general cooling.

I am aware that many modifications of my invention may be made without departing from the spirit thereof, and I do not wish to be limited to the circumstantial terminology of the specifications but rather solely by the scope of the appended claims.

What I claim is:-

1. A brake drum having a braking portion and a mounting portion, said drum being open at the end opposite said mounting portion, and having ribs across said braking portion, said ribs decreasing in height toward said open end.

2. A brake drum having a braking portion and a mounting portion, said drum being open at the end opposite said mounting portion, and having spiral ribs across said braking portion, said ribs decreasing in height toward said open end.

3. A composite brake drum comprising, in combination, a cast braking ring, and a pressed metal mounting plate, said braking ring having ribs on a surface thereof, said ribs extending angularly across said surface, and decreasing in height away from said mounting plate.

4. In a brake drum having a braking portion, a mounting portion and an interconnecting portion, and an open end away from the mounting portion, ribs extending angularly across said interconnecting portion and said braking portion and being of decreasing radial extent throughout the braking portion toward the open end of the drum.

5. A brake drum having a braking portion and a mounting portion, said drum being open at the end opposite said mounting portion, and having a marginal flange adjacent said open end, and having ribs across said braking portion, said ribs decreasing in height toward said open end, said marginal flange being perforated whereby to continue the flow of air induced by said spiral ribs.

6. In a combined apertured disk-wheel, wheel rim and cylindrical brake drum, in which the rim overlies the drum in substantially parallel spaced relation, the combination of angularly extending ribs on the outer peripheral surface of the drum arranged to induce a flow of air through the wheel apertures across the drum surface, said ribs extending through the space between the rim and the drum in decreasing radial extent toward the axially inner end of the space between the rim and drum to form, with the apertures in the wheel-disk and the adjacent surfaces of the rim and drum, an air passage of increasing cross section from the apertures in the wheel-disk to the axially inner end of the space between the rim and drum.

WARREN H. FARR. 

